Help with CPU/GFX choices for HTPC

[DrVik]

Hi everyone,

I'm looking for advice regarding CPU and GFX card choices for a mythtv frontend/backend combo....

My ultimate goal is to have a frontend driving my Sony 1292Q either via RGBHV or via the new IFB-DVI module at 1920 x 1080 while simultaneously displaying the exact same image on a Xenarc touchscreen. The reason for this is that way I won't have to fire up the projector just to play Cds/MP3s. I would also like this frontend to have the grunt to decode and postprocess HDTV signals. The ability to do PIP with 2 HDTV signals would be nice too, but not essential.

I have been led to believe that the Pentium 4 range is the bees knees when it comes to multimedia encoding/decoding mainly based on Brandon Beattie's very informative HTPC Guide. In there he argues against using even AMD64 CPUS for this intensive task. However over at Anandtech the "Linux Desktop CPU Roundup: Cutting Edge Penguin Performance" article shows how nicely the 64bit chips perform on a 64bit OS (Gentoo is what I use). Of course, when it comes to the heat issue, AMD64 with it's lower power dissipation and Cool'n'Quiet technology is a step ahead! So my question is this.... Does anyone know of a head to head shootout in playback and postprocesing, or does anyone have any empirical evidence/experience to offer? I want the top performer for this task and will even accept a Pentium4 with all it's heat issues if it offers a substantial performance margin.

On the GFX card front, I would like to utilise XvMC assist in decoding these streams (rules out ATI right?? ). I notice the newer Nvidia 6x00 series have a lot more MPEG2/4 decoding stuff built into them. Does nvidia make use of this with their linux drivers..? If not, will they ever?? Will a MX440 decode just as well as a 6600??? Does the GPU speed/pipeline width etc actually affect 2D performance/decoding?? Does anyone know of a head to head comparison to guide these decisions?? Also, I presume that PCI express is not a requirement for a frontend and that AGP will do the job just fine. Do the NVidia cards offer the appropriate resolutions (1920 x 1080) via the DVI port?? And will they allow me to send the same image via the VGA port in a different resolution so the Xenarc Toushscreen can understand it??

Thanks for listening and look forward to some answers! :)

drvik
PS: I had links in to help illustrate my point but it's my first post so I can't post URLs :mad:

[shigaloo]

i think you are going to have a problem sending 1920x1080 to a xenarc touchscreen

if you are looking for low power/heat consider pentium m as well, they do quite well on Linux

FYI - We have gotten XVideo (and dual independent displays) working with the latets ATI X.org drivers in debian instable, just takes lots of tweaking and testing.

There are some nice mini-itx boards out there with LVDS on board if you want to go with a small TFT

good luck

[motulal]

My suggestion is to go with an AMD64 and an nVidia 6x00 gfx card.

Make sure that the motherboard only has two memory slots otherwise you will not be able to use the Cool'n'Quiet feature.

The AMD64 comes out ahead of the P4's on Linux since you can compile most of the software for the chip. On Windows, the P4's edge out the AMD64's slightly due to the optimization of the software build for the Intel P4's.

The latest nVidia binary drivers for Linux are almost identical to the Windows drivers. They do take advantage of the onboard mpeg2/4 decode assist hardware.

The ATI drivers for Linux are currently severely lacking and are not worth the hassle.

Unfortunately, I do not have links to post but my latest two HTPC's (mythtv) have been AMD64 3200+ and P4 3.2GHZ based. The AMD64 3200+ beats out the P4 3.2GHZ.

Enjoy

/// Motulal

[DrVik]

Thanks guys,

Motulal: Do you have a link for any articles that discuss the 2 memory slot issue??? My impression was that just about every AMD64 mainboard had 4 slots! Edit: Good article on silentpcreview.com called "Cool'n'Quiet Athlon 64 Motherboards" explains the 2 slot thing in detail.... seems to only affect socket 754 motherboards...

I would also love to hear more about your AMD64 vs Pentium4 experiences... how exactly does the AMD beat the Intel???

drvik

[chrisbirkinshaw]

Originally posted by shigaloo
FYI - We have gotten XVideo (and dual independent displays) working with the latets ATI X.org drivers in debian instable, just takes lots of tweaking and testing.

How does the independent display thing work - if for example your main screen is 1280x720 (e.g projector) and your second screen is 800x600 (touchscreen) what happens to the image?

[wolrahnaes]

I think by independent display he means completely separate...

I don't know of any major UIs that can handle driving dual displays at different resolutions with the same image and still have it look right. That would require fully vectorized rendering, which isn't available yet.